This invention pertains to a wind driven electric power generating system intended primarily for supplying electric power, when wind conditions allow, to a network to which other power generating equipment is coupled.
Conventional wind powered generators comprise a propeller that turns a shaft which is directly coupled to the input shaft of a speed changing mechanism whose output shaft is coupled to the shaft of a rotor in an electric generator. It is believed that in the prior art an anemometer operated switch is employed to complete a circuit to a power network to cause the generator to operate as a motor and get the gear box up to synchronous speed. However, use of a remote anemometer does not provide an accurate sensing of the wind conditions on the wind generator propeller. There is a switch in a circuit between the output terminals of the generator and the network or general electric power system which switch is operative to disconnect the generator from the power lines when wind velocity is low so the generator does not run as a motor and draw power wastefully from the system. In prior art systems, when the propeller is turning at a speed which would result in the generator going up to synchronous speed but the generator is at a standstill at this time so a severe shock is created in the generating system. This is because the rotor of the generator has a high inertia which, in a sense, is amplified by the speed changer that is interposed between the rotor shaft and the relatively slower turning propeller shaft. There is not only a mechanical shock to the system, but it also takes time for the generator rotor to accelerate up to the power system or network synchronous speed which means, that during acceleration time, the output voltage from the generator will be out of phase with the system to which it connects. This can cause undesirable transient current to flow.